Several 2020 Democrat presidential candidates donated just a small sliver of their income to charitable causes in recent years, their tax returns show.

Former Texas Congressman Robert Francis “Beto” O’Rourke released a decade of his tax returns on Monday, revealing that he and his wife donated only a small sum to charity in 2017.

Encompassing 2008 through 2017, the hundreds of pages of returns show that the former Texas congressman and his wife, Amy, had a total annual income of more than $330,000 from 2015 to 2017. His effective tax rate for 2017 was 22%. In 2008, their joint income was around $280,000.

The O’Rourkes paid about $81,000 in taxes in 2017 on an adjusted gross income of nearly $366,500. The couple did not give much of their income to charity, donating only about $1,200 in 2017, amounting to just one-third of one percent. The couple donated less than $900 each in 2016 and 2015.

In a statement, O’Rourke’s campaign said it would be making his 2018 tax returns public “as soon as possible after they are filed.”

O’Rourke’s father-in-law is a well-known developer in his native El Paso, Texas, and O’Rourke’s past financial disclosure records filed during his three terms in the House had previously shown that he and his wife had sold real estate and other assets worth more than $1 million.

O’Rourke joins Sen. Bernie Sanders (I-VT) and several other high-profile Democrats vying for their party’s 2020 presidential nomination in releasing years of past tax information.

Sanders’ 2018 return reveals that he and his wife, Jane, earned more than $550,000, including $133,000 in income from his Senate salary and $391,000 in sales of his book, Our Revolution: A Future to Believe In. The senator’s status as a millionaire, which he acknowledged last week, was cemented in his 2017 statement. That year, Sanders disclosed $1.31 million income, combined from his Senate salary and $961,000 in book royalties and sales.

Sanders and his wife Jane donated $19,000 to charity from their income of $566,000 last year, amounting to roughly 3.4 percent. In 2017, the couple gave $36,00 to charity. However, according to the Washington Post’s Sean Sullivan and Michael Kranish, the Sanders campaign stated, “those rates do not reflect charitable proceeds given from one of his books, which he did not deduct from his taxes.” The Post reports that the campaign did not provide a figure for how much was given to charity.

On Sunday, Sen. Kamala Harris (D-CA) released 15 years of tax returns. Harris and her husband, Doug Emhoff, a partner at the law firm DLA Piper, took in $1.9 million last year, but dolled out only $27,000 to charity or 1.4 percent. In her first three years as California Attorney General, Harris reported no donations to charity. Sen. Kirsten Gillibrand (D-NY) and her husband earned $215,000 last year and donated under 2 percent of their income. Further, Sen. Amy Klobuchar (D-Minn.) and her husband made $338,500 last year and donated only $6,600 to charity.

Sen. Elizabeth Warren (D-MA) and her husband appear to be the most generous of the Democrat White House hopefuls, donating $50,000 last year on $906,000 of income, amount to 5.5 percent.

The Associated Press contributed to this report.